Prior art methods and systems for separating upper and lower turbine shells involve utilizing the rigging art of blocking and jacking in multiple steps to separate the upper and lower turbine shells to the desired distance. Separate jacks have typically been used at, for example, the four corner locations of a turbine and care must be used by the operators of the jacks so that each corner is lifted at the same rate to the same distance. When the ram height of each jack has been extended to nearly its full travel, the turbine shell is blocked firmly in place and the ram is retracted. Next the ram is blocked for its next jacking cycle. This process is repeated 3–4 times depending upon the unit geometry.
FIG. 1 shows upper and lower turbine shells 11 and 12 of turbine 10, and ram access pockets 13 located at the four corners of upper turbine shell 11 (only two ram access pockets are shown). As will be appreciated by those skilled in the art, it is a time consuming and difficult task to ensure that each corner of upper turbine shell 11 is lifted uniformly, at the same rate and for the same distance, away from lower turbine shell 12. Many adjustments are required by the operators during the process to ensure that each jack ram has created the identical level of separation as the other jack rams.
The hydraulic jacking hardware that is typically identified on the wrench and tool list supplied by the turbine manufacturer will only support the above described blocking and jacking process. The pumps and hydraulic rams usually have an effective travel of about 3–4 inches.
Moreover, the typically used manual hydraulic pumps do not have the oil capacity to handle the use of taller telescoping hydraulic cylinders. Also, the access pockets are not tall enough to accommodate the use of larger telescoping rams. Thus, the prior art systems and methods must procure blocking to be used in the step jacking procedure for both the shell and for underneath the ram. This process is labor intensive.
Millwrights working in a team of 8–10 will call out measurements in increments of ⅛ inch until the ram has reached its extended travel. This process is not very accurate for controlling the parallelism of the shell separation. Accordingly, use of prior art systems and methods have frequently caused damage to the radial fits of the turbine shells because of uneven separation of the horizontal joints.
To assist the jacks, a main crane must be hitched to the upper shell to maximize the separating force being applied. The shell is then slowly jacked and lifted until sufficient height is obtained for adjusting the rigging hitch to remove the upper shell. Currently millwrights block and jack the upper half shells about 10–12 inches before they are free of all radial fits. Then they adjust the crane rigging to a level hitch before lifting the shell. When the shell can be positioned free of all the radial fits the hitch levelness is not as critical.